This invention relates to sofa bed mechanisms and more particular a sofa bed mechanism mounted within a sofa frame for movement between a horizontal bed position and a folded sofa position.
U.S. Pat. No. 4,509,216, assigned to the assignee of the present invention, describes such a sofa bed mechanism. Among the objects of conventional sofa bed mechanisms is to provide firm, stable support for users in the bed position. Unfortunately, conventional sofa bed mechanisms tend to fold up when a downward force is applied to the extended folding mechanism at a position at the head section of the sofa bed mechanism. This can be quite disconcerting to the user of the sofa bed, and usually occurs when the sofa bed occupant is in a sitting-like position near the head of the bed.
It is therefore an object of the present invention therefore to provide an improved sofa bed mechanism with a locking feature that provides a stable sofa bed platform when a load is applied to the head section.
It is another object of the invention to provide a sofa bed mechanism which transmits a portion of the downward force exerted on the head section to the foot section to maintain the sofa bed mechanism in the horizontal bed position.
The present invention provides a sofa bed mechanism with a foldable bed frame which includes in succession a head section, an intermediate section and a foot section, each joined at their ends and movable between a horizontal bed position and a folded sofa position. The foldable bed frame is attached to a support member. A folding mechanism is attached between the foldable bed frame and the support member and includes a rear linkage assembly on the support member which is operable to control the movement of the bed frame between the bed and sofa positions.
The folding mechanism further includes a pivotal leg extending from each of the foot and intermediate sections, a front linkage assembly connected to the legs and to the rear linkage assembly for moving the legs into a downwardly extending support position in response to movement of the bed frame into the horizontal bed position, and means extending between the front and rear linkages which maintains a downward directed force on the legs to prevent the folding of the bed frame from the horizontal position to the folded sofa position in response to a downward load applied to the head section.
The rear linkage of the folding mechanism includes an elongated suspension arm which has one end pivotally connected to the head section, an elongated connecting link connected to one end of the suspension arm and a first and second parallel arm each having one end pivotally connected to the support member. The other end of the first parallel arm is pivotally connected to one end of the suspension arm. The other end of the second parallel arm is pivotally connected to the other end of the connecting link.
A cross link member is connected to the other end of the first parallel arm and the second parallel arm. The cross link maintains the parallel arms in parallel relation as the folding mechanism is moved between the horizontal bed position and the folded sofa position.
An elongated lock out bar extends between the front linkage and the rear linkage assemblies. The lockout bar has one end pivotally attached to the suspension arm attached to the head section and has its other end pivotally attached to a leg locking strap in the front linkage assembly which is pivotally attached between the leg pivoted from the foot section and the intermediate section whereby the lock out bar connected between the suspension arm and the lock out strap exerts a downward force on the strap when a downward force is exerted on the head section thereby preventing the suspension arm from rotating counterclockwise to fold the bed frame when downward force is exerted on the head section.
The front linkage assembly of the folding mechanism according to the present invention further comprises a front leg brace member which is connected between the leg pivoted from the foot section and the locking strap. This brace member is pivotally connected to the leg at a point below the leg's pivot point such that a downward force on the locking strap placed thereon by the lock out bar pulls the leg downward to maintain the bed frame in a horizontal position.
Thus if a person were to sit on the head section or otherwise exerts a downward load on the head section on the folding bed frame when it is in the horizontal bed position, a portion of the downward force is transmitted to the force legs via the suspension arm, the lock out bar, and the leg locking strap to lock the folding mechanism in the horizontal position. This makes the folding sofa bed mechanism safer to use and more stable under all load conditions.
Further objects, features and advantages of this invention will become apparent from a consideration of the appended claims, the following description and the accompanying drawing.